Defrost puff pastry (both sheets) at room temperature for 20-30 minutes or until pliable. Meanwhile, prepare filling. Place steak, flour, salt and pepper in a large plastic bag and shake to coat well. Add onion and mushrooms to the bag and shake to mix. Pour ingredients from the bag into a standard 9-inch pie plate, mounding high in the middle. Nestle the pie bird, if using, into the center of the mixture. Roll out one of the pastry sheets onto a lightly floured surface to remove creases and enlarge the size of the sheet just enough to cut an 11-inch circle from its center. To cut a circle, invert a clean 9-inch pie plate (the plate will actually measure 10 inches from edge to edge) onto the sheet of pastry. Using a very sharp knife, trim the pastry 1 inch away from the edge of the plate, forming a picture perfect 11-inch circle. Now, come in about 2 inches from the rim of the circle and cut a smaller circle (this one does not have to be so exact), forming a 2-inch ring of pastry with an 11-inch diameter. Got it? Great. Oh, hold on to those pastry scraps. We'll turn them into beautiful leaves that go on top of the pie. Brush the edge of the meat filled pie plate lightly with water to dampen, then center the pastry ring over the rim of the plate, leaving about a 1/2 inch overhang (for crimping or "knocking-up" as they say in Great Britain!) Tuck the pastry ring slightly down into the sides of the pie plate, forming a "mock" bottom crust. This will help keep the crust secure from leaks. Now, slowly pour the beef broth over the meat, allowing time for the broth to settle to the bottom of the dish. Try not to pour the broth over the edge of the bottom crust. Roll out the remaining sheet of pastry, again, just large enough to cut out a circle with an 11-inch diameter to use as a top crust. If you are using a pie bird, cut a small "x" into the center of the top crust, to allow you to wiggle the pastry easily over the bird. If you don't have a pie bird, simply cut some decorative slits in the top crust, after assembling, to allow steam to escape while baking! Lightly brush the rim of the "bottom" crust with water, then arrange the top crust over the filling. Press edges firmly together, then "knock-up", crimp or flute as you'd like. Now, you can cut your decorative slits, if you are not using a pie bird. Cut leaf shapes from pastry scraps and score "veins" with a sharp knife. Dampen the back of leaves and arrange over the top crust around the pie bird. Lightly beat an egg white with about a tsp of cold water until frothy, then brush evenly over the tops of the leaves and the top crust. Bake in the center of a preheated 450F oven for 10 minutes or until crust is puffed and lightly golden. Then reduce oven temperature to 350F and move pie to a lower rack. Continue baking another 60 minutes. Cover pie loosely with foil if crust becomes too brown.
YIELD: 6 servings